This summer, Coca-Cola kept fans and cans cool with an exciting packaging evolution that tells consumers when their Coke is perfectly chilled.

Across parts of Western Europe, the Coca-Cola system introduced colour-changing packaging with temperature-sensitive labels that transform the Coca-Cola logo from classic white to blue and pink when the can or bottle is perfectly chilled at 4°C.

The label activation was part of our summer drive to put Coca-Cola in the hands and hearts of people across Europe, and make their summer moments even more special. To help spread the message that nothing beats an ice-cold Coke on a hot summer's day, we set the point of colour change to reflect the optimal temperature for consumption.

Best served cold

Sanjay Patel

So, what's the science behind this innovative packaging feat? Thermo-chromatic ink, explains Sanjay Patel of our global packaging research and development (R&D) team, and the man behind the label technique.

"The principle is simple," said Patel, who is based in Brussels.

"We use colour-changing molecules in the ink used for the packaging decoration. These molecules transform when they reach a certain temperature. At room temperature, they are colourless, but as soon as the temperature drops, the individual pigments start to become visible. The process begins at 12°C and the colours reach their optimum vibrancy at 4°C – corresponding with the perfect serve for a Coke."

A total of 290 million packs of Coca-Cola, Diet Coke, Coca-Cola Life and Coca-Cola Zero Sugar were used in the thermochromic activation across parts of Western Europe to provide fans with the ultimate refreshment.

Behind the launch of the temperature-sensitive packaging lies an impressive operational exercise. Our supply teams worked together to deliver the right technical solution at the best possible cost.

Following a pilot in Australia in 2015, the labels made their European debut in the Netherlands in May, where feedback from fans was very positive. They are now being used in Norway, Denmark, Finland, Germany, Iceland and Ireland.

"The biggest challenge was making the thermo-chromatic ink technology economically viable while preparing our 17 packaging suppliers for the technology in our Western Europe markets, and all within the seven-month project timeframe from brief to launch,” Patel explained.

"It shows the amazing things we can achieve when we work together as a team." - Sanjay Patel

Meanwhile, software company Evrythng developed a scanning app that lets consumers interact directly with the packaging.

“Consumers can instantly scan the chilled packs with their phones to win prizes, without downloading a special app," Patel said. "This played an important role in the success of the activation, but meant we were working on two different but related fronts at the same time, as one can’t work without the other.”

Due to the scale and speed to market, the project required a massive collaborative effort between the different departments in Coca-Cola and our bottling partner Coca-Cola European Partners, led by Jodie Sharp, commercialisation project manager at CCEP.

"The system pulled together really well," Patel said. "It shows the amazing things we can achieve when we work together as a team."

Thermo-chromatic ink isn't new – the technology has been around for 30 years, but up until now it was only available in small volume activations. We're now the first to launch the technology on a mass scale.

"Since the start of the project, we have received inquiries from colleagues around the world who are all looking to replicate the technology in their markets," Patel said. "We see a lot of potential for the packaging innovation in the future."